Auto merge of rust-lang#127173 - bjorn3:mangle_rustc_std_internal_symbol, r=wesleywiser,jieyouxu

Mangle rustc_std_internal_symbols functions

This reduces the risk of issues when using a staticlib or rust dylib compiled with a different rustc version in a rust program. Currently this will either (in the case of staticlib) cause a linker error due to duplicate symbol definitions, or (in the case of rust dylibs) cause rustc_std_internal_symbols functions to be silently overridden. As rust gets more commonly used inside the implementation of libraries consumed with a C interface (like Spidermonkey, Ruby YJIT (curently has to do partial linking of all rust code to hide all symbols not part of the C api), the Rusticl OpenCL implementation in mesa) this is becoming much more of an issue. With this PR the only symbols remaining with an unmangled name are rust_eh_personality (LLVM doesn't allow renaming it) and `__rust_no_alloc_shim_is_unstable`.

Helps mitigate rust-lang#104707

try-job: aarch64-gnu-debug
try-job: aarch64-apple
try-job: x86_64-apple-1
try-job: x86_64-mingw-1
try-job: i686-mingw-1
try-job: x86_64-msvc-1
try-job: i686-msvc-1
try-job: test-various
try-job: armhf-gnu

Author: bors

alloc/src/alloc.rs

@@ -10,25 +10,28 @@ use core::ptr::{self, NonNull};
 
 unsafe extern "Rust" {
     // These are the magic symbols to call the global allocator. rustc generates
-    // them to call `__rg_alloc` etc. if there is a `#[global_allocator]` attribute
+    // them to call the global allocator if there is a `#[global_allocator]` attribute
     // (the code expanding that attribute macro generates those functions), or to call
     // the default implementations in std (`__rdl_alloc` etc. in `library/std/src/alloc.rs`)
     // otherwise.
-    // The rustc fork of LLVM 14 and earlier also special-cases these function names to be able to optimize them
-    // like `malloc`, `realloc`, and `free`, respectively.
     #[rustc_allocator]
     #[rustc_nounwind]
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_alloc(size: usize, align: usize) -> *mut u8;
     #[rustc_deallocator]
     #[rustc_nounwind]
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize);
     #[rustc_reallocator]
     #[rustc_nounwind]
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8;
     #[rustc_allocator_zeroed]
     #[rustc_nounwind]
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8;
 
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     static __rust_no_alloc_shim_is_unstable: u8;
 }
 
@@ -357,6 +360,7 @@ unsafe extern "Rust" {
     // This is the magic symbol to call the global alloc error handler. rustc generates
     // it to call `__rg_oom` if there is a `#[alloc_error_handler]`, or to call the
     // default implementations below (`__rdl_oom`) otherwise.
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_alloc_error_handler(size: usize, align: usize) -> !;
 }
 
@@ -423,6 +427,7 @@ pub mod __alloc_error_handler {
         unsafe extern "Rust" {
             // This symbol is emitted by rustc next to __rust_alloc_error_handler.
             // Its value depends on the -Zoom={panic,abort} compiler option.
+            #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
             static __rust_alloc_error_handler_should_panic: u8;
         }
 

panic_unwind/src/lib.rs

@@ -79,9 +79,11 @@ cfg_if::cfg_if! {
 unsafe extern "C" {
     /// Handler in std called when a panic object is dropped outside of
     /// `catch_unwind`.
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_drop_panic() -> !;
 
     /// Handler in std called when a foreign exception is caught.
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_foreign_exception() -> !;
 }
 

std/src/alloc.rs

@@ -348,6 +348,7 @@ fn default_alloc_error_hook(layout: Layout) {
     unsafe extern "Rust" {
         // This symbol is emitted by rustc next to __rust_alloc_error_handler.
         // Its value depends on the -Zoom={panic,abort} compiler option.
+        #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
         static __rust_alloc_error_handler_should_panic: u8;
     }
 

std/src/panicking.rs

@@ -55,12 +55,14 @@ pub static EMPTY_PANIC: fn(&'static str) -> ! =
 // hook up these functions, but it is not this day!
 #[allow(improper_ctypes)]
 unsafe extern "C" {
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_panic_cleanup(payload: *mut u8) -> *mut (dyn Any + Send + 'static);
 }
 
 unsafe extern "Rust" {
     /// `PanicPayload` lazily performs allocation only when needed (this avoids
     /// allocations when using the "abort" panic runtime).
+    #[cfg_attr(not(bootstrap), rustc_std_internal_symbol)]
     fn __rust_start_panic(payload: &mut dyn PanicPayload) -> u32;
 }